PIN Diode Ratings

This photosensor:

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C156.pdf, lists a short circuit current of 90uA with a 100 foot-candle illumination.

I'm considering it for an application where we'd be controlling a light source, and it would make our jobs easier if the illumination were much higher, with equally higher currents in the device. I'm _assuming_ that it'll work fine and dandy at higher illuminations (and currents), at least until heating gets to be a problem.

Am I all wet? Are there reasons that this wouldn't stay reasonably linear at 10x or even 100x the illumination that it lists? What are the limits? Does the thing start to go into some sort of a current saturation mode? Does it start to look like a plain resistor at too high of a current, etc.?

Thanks.

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Reply to
Tim Wescott
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Internal series resistance will limit current in photovoltaic mode. That's less a problem if you bias it.

John

Reply to
John Larkin

It'll be used in photoconductive mode.

The problem is that it is specified at 100 fc and 90uA. I'd really like to start at 1000fc or even 10000 for the top end of my range, and go down from there. That would make the rest of my circuit design far easier.

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Reply to
Tim Wescott

Well, you'll have to test it, with a light meter or something. It doesn't sound to me like 900 uA is a lot of current, or maybe even 9 mA. Keep the voltage down to limit power dissipation; that will cost you a little speed.

Got a link to the part? How fast does it need to be?

PDs have a huge dynamic range; see Phil's book.

John

Reply to
John Larkin

Yes, in my original post.

I was hoping that Phil would answer!!

Maybe he's off being productive. Scary thought.

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Reply to
Tim Wescott

Eventually it'll run out of electron-hole pairs it can generate. See figure 3-3 here:

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Unfortunately the datasheets of many photodiodes leave a lot to be desired, I'd consider them incomplete. They usually do not mention saturation. You could bug the manufacturer for some more data or just try it out. Give it a heavy dose of reverse bias but stay clear of the point of *PHUT* :-)

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Reply to
Joerg

Um. Well. Technically, yes.

That's a huge chunk of silicon. It shouldn't mind a few mA.

Um. Well. Technically, yes.

John

Reply to
John Larkin

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I've got a PD with about twice the area. (0.25 inch diameter circle). I can get currents above a few mA out of it, but it's no longer linear. (doubling the intensity does not double the current.) The blurb in the manual says it becomes non-linear above 0.5mA, but that somewhat depends on how the PD is illuminated. (laser spot or spread out beam.) (the manual was written ~ 10 years ago and it would be easier to redo the experiments rather than going to try and dig up the data.)

George H.

Reply to
George Herold

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cottdesign.com

Oh, this is configured with no bias voltage across it... Grounded PD into a TIA opamp. (If that makes a difference? also waiting for a response from PH the PD sage.)

Geo

Reply to
George Herold

Years ago I moved to TAOS sensors. for us, a much cheaper and easier way of visible light level sensing. Use many thousands of the TSL2569T device. Takes the hassle out of daylight linked dimming for luminaire control. The only PIN photodiodes I use are in our photometer. 37 of these:

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Reply to
JB

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It does.

Yeah, how could he just leave without this group's permission? :-)

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Joerg

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"Shouldn't mind" is pretty subjective and smacks of opinion.

Do you have some actual data WRT similar photodiodes or are you, as
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John Fields

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John Fields

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That must have been before his affair :-)

Wasn't Debussy the "wild one"?

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Reply to
Joerg

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Driving home I remebered I use a little PD from OSI (PIN3-cd) 1.2 x

2.5mm. I can get more than 1 mA out of it, But I have no idea if it's linear at those currents. But maybe Tim doesn't need linear.

Oh and it is reversed biased. ~15V (designed after reading PH's book.)

George H.

Reply to
George Herold

You expected Larkin to cite FACTS ?:-)

You already know the answer :-) ...Jim Thompson

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Reply to
Jim Thompson

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Christmas light project?

Reply to
Fred Bloggs

Of course it's opinion. I haven't tested any of this particular diode. But I have a lot of history of using silicon and compound-semi photodiodes. How about you?

Remember when I wild-guessed the contact times of your steel ball collision thing, and was dead on? I'm pretty good at estimating numbers that way.

I have used much smaller photodiodes which the makers rated for a couple of mA, but in fact were linear at massive illuminations, hundreds of mA.

Good photodiodes are linear over many orders of magnitude. Like 9 or so.

You're just sniveling about stuff you know nothing about. As usual.

John

Reply to
John Larkin

So, say something intelligent about photodiodes. Or alternators. Hell, about anything.

John

Reply to
John Larkin

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John Fields

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